1. Field of the Invention
The present invention relates to a pin milling cutter for crank shafts in which a cutter and adapter are combined.
2. Description of the Background Art
Examples of pin milling cutters include the ones disclosed in Japanese Patent Publication Number 2861828, Japanese Laid-Open Patent Publication Number 2004-283934, Japanese Laid-Open Patent Publication Number 2004-283935, and Japanese Laid-Open Patent Publication Number 2004-314194.
The pin milling cutters disclosed in Japanese Patent Publication Number 2861828, Japanese Laid-Open Patent Publication Number 2004-283934, Japanese Laid-Open Patent Publication Number 2004-283935, and Japanese Laid-Open Patent Publication Number 2004-314194 are all formed by combining a ring-shaped cutter with cutting sections formed on the inner perimeter with an adapter on the outer perimeter of which the ring-shaped cutter is positioned. In the cutter, a replaceable cutting edge insert is mounted on the inner perimeter of a main cutter body, and an edge of the insert forms the cutting section. Also, multiple tapered splines are formed on the outer perimeter surface of the main cutter body in the along the circumference and at a fixed pitch. The tapered splines, which are formed with diminished width toward the front (relative to the direction in which the cutter is inserted to the adapter), are inserted into corresponding spline grooves formed on the inner perimeter surface of the adapter, thus allowing the cutter to fit concentrically with the adapter. A clamper with a partial disc shaped clamp plate is used for securing so that the cutter can be removably mounted on the adapter.
Because of the diversity of user needs, cutting operations performed with pin milling cutters can often involve cutting multiple workpieces with similar dimensions and shapes in a single workplace. In the production lines of car manufacturers, a specially assigned operator from a specialized division generally performs the replacement of inserts when an insert has reached the end of its lifespan. However, when inserts with similar shapes are present in a cutter which has had its cutting edge replaced, an inappropriate cutter may be installed on an adapter by mistake. This will result in all the cut parts being defective.
In pin milling cutters formed with intermeshing tapered splines and tapered grooves on the cutter and the adapter, the fitting precision of the intermeshing sections (the tapered fitting sections) is often maintained through gauge inspections due to the requirements of repetitive production. While cutters with high-precision engagement sections can prevent inappropriate combinations of cutters and adapters by using different widths, outer diameters, and shapes for the tapered splines and spline grooves, using this method will increase the number of types of engagement sections and will lead to issues such as the inconvenience of gauge inspections, production costs, and administration.
The object of the present invention is to prevent mistakes in the attachment of cutters to adapters even if different types of cutters are similar and even if the engagement sections of these cutters and adapters are the same.